His Older Twin Sister, Her Younger Twin Brother
by NewBloom
Summary: Tsuna has a secret. That Secret? A man named Iemitsu, and a girl named Aemi. Tsuna doesn't want to keep the Mafia a secret from Aemi, but She has secrets too. She's going to be boss with Tsuna, and she'll also fall in love, with a guy no one expected.
1. Chapter 1

She smiled indulgently at the little dark-haired girl beside her who stood on her seat to see if anyone she knew was on the plane, her brown eyes gleaming with excitement. The little child giggled when her father's arms came out from the row behind her and wrapped around her. They had been forced to sit apart due to lack of seating.

He picked her up over the seat and held her carefully. The woman smiled the entire time even as she held her sleeping son ever closer to her chest.

I suppose most people would assume that this story is about the woman, but it isn't, this story is about the twin sister of the boy sleeping in her arms, who happens to be the giggling girl snuggled with her father.

Now I guess I will give you some names to fit the descriptions. The woman is Nana, The man, Iemitsu, the boy, Tsunayoshi, and his twin sister is Sawada Aemi.

She isn't all that strong or important yet, at the age of 7 she has no idea that her father is in the mafia, and that her and her brother are candidates for the position of Vongola Boss. She won't know for many more years. Specifically, she won't know until she's thirteen, when her father will take her away from her quiet home in Naminori to travel to Unexpected Italy.

She will however, be secretly trained by her father her whole life without her even knowing, him sneaking up on her and attack hugging her, signing her up for Karate, fencing, and Kendo training, Sparing with her every chance he got and having her work on meditation for concentration and determination.

When she does get to Italy, she will learn it all, and accept her role, knowing that she won't even be considered for Vongola boss unless all the others die before her. She will find out, when she's fifteen that the others have all died and her and her brother are the only options left, and she will tell them that she will never be Boss without her brother by her side.

She will return home with her father, and she will carry a ring. The ring that had always been prepared for a twin sibling to wear, because this was not the first time such a situation had arisen, the first Vongola boss also had a twin sister, but his had died shortly after the ring had been made. She isn't what Tsuna and their guardians expect either, Tsuna hasn't seen her for years, and she has never met the others, Aemi will wow them all.

~~~~Current Time~~~~

Yanking hard, I finally managed to free my bag from under the pile of suitcases. It really was just my luck that the plane I was on had to belly land and ended up dumping all of our stuff on the ground.

My father groaned from the ground behind me. "Aemi? You alright?" I spun on the spot before offering my father my hand to help him off the ground.

"Yes, I am fine, missions with the Varia quite often end with situations such as this" My voice came out muffled and tangled and I made a dull disgusted noise in the back of my throat, after two years of speaking only Italian, my ability to speak Japanese had become severely lacking.

My father sighed in relief before realizing what situation we were in. His awareness of reality came suddenly flooding back, he blinked and finally grabbed his bag before slinging it over his shoulder. I stuck my arm once again deep into the pile to rescue my carry on bag.

I sighed upon pulling it out, I could hear the tinkle of broken glass within. "So it seems my present for mom didn't survive, well, at least I have the metal one still" I too slung my duffel over my shoulder before scanning the familiar areas nearby, The airport was set upon one of the sole hills in the area and seeing my old home brought a smile to my face. I missed my twin brother desperately, two years could do that to someone.

"Let us go home Father" I said as I slung my arm around his neck "We have been gone for much too long of a time"

***At Tsuna's Home***

-Tsuna's POV-

Gokudera patted me on the back hard before turning away, His voice was muffled when he spoke "Sorry Juudaime, but my sister is there and you know what it's like when she's there…" He dropped his head in embarrassment and slunk away, depressed to have to leave.

"Maa maa, We'll be fine, right Tsuna?" Yamamoto said with a carefree grin on his face and I was glad for the reassurance, seeing my dad's stuff was freaking me out a little more then I would've liked to admit.

I walked in and saw Bianchi who then told me that Mom was getting food because Dad ate it all, and then I saw Lambo, I-pin and Fuuta, all incredibly drunk. I ran to the back of my house with Yamamoto trailing calmly behind me, after slamming open the door my jaw dropped in surprise and disgust.

"What is he-" I paused "Wait…? If dad is here then that means…" A sudden light bulb went off in my head. I ran even faster then before if possible to get to the bedroom beside mine which had stood empty for two years, and sure enough when I slammed open the door I saw exactly who I had hoped to see "Aemi-nee" I said softly before launching myself on her.

-Aemi's POV-

"Ugh… Imouto! (Younger brother) I have not even had a chance to finish unpacking yet!" I sighed but still, I wrapped my arms tightly around him and hugged him hard "I missed you Tsu-kun" He hugged me back.

"I missed you too Aemi-nee" Finally, after about a minute I pushed him away.

"So who is your friend?" I said as I sat on the edge of my bed and gestured for his black-haired friend to enter the room.

"Yamamoto Takeshi" The black-haired g- I mean, Takeshi-san said. "And you are?"

"It is a pleasure to meet you, I am Sawada Aemi, Tsunayoshi's elder twin sister" Takeshi-san rubbed his head nervously.

"Um.. If you're really his sister, then why have I never met you before?" I laughed in response to his question where as he blushed.

"I've been in Italy with my father for two years, and before that I went to a private school for physical training" His smile returned even though he was still bright red.

"Well it's nice to meet you, will you be going to school with us anytime soon?" He paused "Or are you going back to private school?" I bit my lip, I had a response but they didn't know about the half-Vongola rings battle yet, so I couldn't tell them.

"In a couple weeks" I answered vaguely. "I need to get settled back into my home first"

Tsuna smiled and got up from the floor where he sat and I stood as well. "I might walk Tsuna to school tomorrow anyways, so I'll see you then" I said as I quite obviously pushed the two of them from my room. I paused before slamming the door in their faces "Bye!"

I turned and slumped against the door "Thank god they're gone, I don't know how I would've explained had Tsuna seen the content of the bag I was unpacking" Pulling myself up again I returned to my bag to finish unpacking my weaponry. What with the whip, the sword, and the daggers, let alone the guns and rifles, Tsuna would've freaked.

I fingered the half-ring hanging on my necklace. I suppose, Tsuna doesn't need to know about any of this yet.


	2. Chapter 2

"TSU-KUN!" I yelled as I leaped on top of him in bed. "WAKEY WAKEY EGGS AND BAKEY!" He groaned.

"Aemi-nee? What time is it?" I grinned

"Time for you to get ready for school, now up we get!" I said as I wrapped my legs around his waist and my arms around his chest before proceeding to roll the two of us off the bed. I stood up afterwards but Tsuna finally opened his eyes.

" Fine, I'm getting up" I sent a smile his way before turning to walk out, I paused at his door.

"Mom already made breakfast so hurry done, okay?"

~~~~~~ THIS IS THE AUTHOR SKIPPING THE WALK DOWN TO THE KITCHEN BECAUSE SHE DOESN'T FEEL LIKE WRITING IT!~~~~~~

I heard a groan from behind my chair, I tossed some toast behind me for Tsuna to catch. "you're late for school, I'm staying here, have fun running" I could feel the glare on the back of my head.

Once he was gone I breathed a sigh of relief "DAAAAAD! WHAT AM I SUPPOSED TO TELL HIM?" I cried out as I slumped forward on the table

"Whatever you want Aemi, you know he won't hate you, he might freak out but that's the way you're little brother has always been" I nodded my agreement before tacking a sigh on.

"Where's Dino? I want to check up on Basil" He grinned and pressed a piece of paper into my hand. I grinned and pulled off my bathrobe, I was fully dressed and everything, but I was certain that Tsuna would have been curious if I was unwilling to walk too school with him but still dressed. I grabbed my bag and began my walk to the hospital.

I pushed open the doors hard expecting to have to wait several minutes to find Dino. With my luck of course, Dino, Reborn, Tsuna, Takeshi, and Gokudera were in there. (Gokudera had always been mafia so whether I had actually met him or not, I already knew he was). I let out a very colourful string of curses out underneath my breath. Mostly because they had all seen me at this point.

"Hey Tsuna! What're you doing here?" I said as I struggled to think up a lie quickly enough. "I was just uh.. Collecting cans for the food drive and I was wondering if anyone here might have any to donate" I said almost wincing from the lie, I knew he would see through it, I had only been back for a day.

Gokudera luckily had left so I didn't have to explain it to someone who I hadn't met but the look Tsuna and Takeshi were giving me was obviously a look which said 'you're lying' I grinned sheepishly before turning on Dino. "DINO! WHAT SHOULD I TELL THEM ? HELP ME !"

Takeshi's face was contorted with a sour expression "Why not start with why you know him?" he had this tone that made him sound like he was accusing me of something.

I winced. Sucking in a long breath I started "I've-really-been-training-with-the-mafia-for-two-years-and-it's-my-fault-that-you-have-to-go-through-this-because-I-refused-to-be-boss-without-Tsuna-by-my-side-SORRY!" I yelled so fast that I could barely understand myself.

"Slower please?" Tsuna asked confused.

"I said that while I was in Italy for two years, I was really training to be the next boss candidate because all the others had died, and a year and a half ago, which if you've forgotten, is when Reborn came to live with you, I told them that I wouldn't be boss of the Vongola without Tsuna as boss with me, I've been training with the Varia and with CEDEF which is why the Varia know where you live, and that the rings got sent to you, because I accidentally let it slip because I didn't think that Xanxus would get a set of the rings as well"

I took another deep breath "So it's really my fault that you went through all of this mess, somehow at the time, I thought that you would love to be boss with me, and that it would all be fun and games." I looked down at my feet "But I was wrong, I was, and still am, a child which doesn't understand the world, but Tsuna, in comparison to my stupid child like behaviour, you would only be a newborn, I'm sorry that I dragged someone as innocent into this world, into my world"

The stared at me uncomprehendingly until I pulled my necklace out and let them see my half Vongola ring. "I have the original Boss ring, you have the one which was made for the first boss' twin sister who died before she could wear hers" Tsuna looked betrayed.

"How could you? Because of you I've spent the last year and a half of my life being tortured by Reborn and forced to train non-stop, and be in battles everywhere, while you get quite cushy training in Italy" I flinched and set my jaw. "I've had to fight for my life at least once and dragged people around me into it simply because I would be dead otherwise, while you get what? To Study by the pool with a cool drink?"

"To get shot at, forced to assassinate people, be sent to live with someone who commits at least weekly attempts at my life, be cut off from my entire family and thrown into a place where I don't even know the language! And that was only parts of Italy. Tsuna, I've been trained my whole life, I was trained in any and all martial arts Dad could sign me up for, sent to the equivalent of a military school just so that I can come out stronger! Perhaps I was stupid and robbed you of fun times in your teenage years but the minute I'm given my childhood back, I promise you I will do anything to fix your teenage years" He paled.

"Tsuna, I've had to fight people to the death before, I had to check everything I ate for fear of poison, I couldn't have a single friend because where I was, there wasn't a single person who wouldn't kill me the second I let down my guard, I'd take it back if I could but stupid or not, I'm still happy that I won't have to be alone anymore" A tear ran down my cheek. I wiped it off. "Anyways what's done is done, hate me if you want but I did actually have a reason for being here"

"Dino, how is Basil?" He smiled, because he knew that I was going to ask about Basil.

"He'll make it through" I relaxed.

"That's good to hear, tell him I say hi, I just needed to make sure he was okay"

"Yeah will do" I waited only barely long enough to hear Dino's last comment before walking back out the doors and into someone wearing a half Vongola ring.

"Oh sorry about that, I didn't see you coming" I said as I helped him up. "you must be one of Tsuna's friends, I'm Sawada Aemi, Tsu-kun's older twin sister"

"Sasagawa Ryohei, it's EXTREME to meet you but I have to go" I smiled at him as he ran by. At least he would probably forget about hating me after a while.

Now I just have to wait for Tsuna to forgive me.


	3. Chapter 3

I gritted my teeth "The Varia" every head snapped my way "Vongola assassination squad, to goddamn smart to fall for fake rings"

"Aemi? I thought you were staying away from Tsuna while he was angry?" Yamamoto cried. I ignored them.

"So which one of you figured it out? 'Genius' Prince the Ripper? Levi 'The boss' right hand man'? Mammon the greedy ass bastard? Or was it your freaking idiot boss Xanxus?" I said as I held my hand up beside my hand to block the blow that I knew Xanxus had thrown at me.

"Long time no see 'Onii-sama' " I spat venomously. "What kind of 'activities' have you been up to lately? Dismembered any nice people recently? Have you gotten any better at maiming people? I remember you always used to fail at maiming me, well of course you still fail at maiming then don't you?" I said throwing my arms wide. "How could you have succeeded? I'm still here aren't I?"

I snorted with disgust "Is this another attempt on my life, or is it an attempt on all of our lives this time? Wouldn't that be a change in pace, instead of those 60 odd assassination attempts in my sleep, I think it'll be a real treat to have someone try and murder me while I'm awake instead" I sat on the edge of the building across from them.

'Ushishishi, Battle Principessa' I heard Bel mutter from across the street.

"Don't even try it, 'My Prince' or else I'll chop of your 'Royal Jewels' got it?" The evil sadistic bastard that he is, he continued to laugh "Oh wow, Belphegor's a masochist, as if no one knew that already, you know he doesn't just start laughing whenever he starts bleeding, oh wait, HE DOES" I suppressed a snort "really, just get our favourite sadistic tonfa wielding prefect in with Prince the Ripper here and they'd have a lot of fun"

Tsuna and the rest of our family were staring at me. "Oh please, I was raised by them for important formative teenage years what did you expect?" Gokudera glared at me.

"You called juudaime's enemy Onii-sama, obviously you're on their side dammit" I huffed before jumping off the edge of the building and landing beside Tsuna.

"I will have you know that I am a 'juudaime' candidate as well, in fact, you might call Tsuna my right hand man, Ahou-dera" Tsuna rolled his eyes and Gokudera's jaw dropped "For that matter you could probably call me Tsuna's right hand woman"

"Stop making fun of him Aemi-nee-chan" I winced at the cold tone in Tsuna's voice.

"Imouto…" I said softly. Finally I tore my eyes away even though it hurt me too let Tsuna still be angry at me.

Moments later, Gokudera finally pulled himself out of his stupor.

"Wait…who are you?" I pretend pouted.

"Really? My own family doesn't know who I am? Oh woe is me, how will I ever survive?" I turned to the Varia who were busy trying not to laugh their heads off. "Hey Xanxus, I changed my mind, I'll take you up on your offer to be Boss together, at least you guys know who I am"

"Too late trash, I already got a replacement" I pretend saluted him.

"Aye Aye captain," I turned back to Gokudera and genuinely smiled. I offered him my hand to shake "Sawada Aemi, Tsuna's twin sister, also the person with whom Tsuna will be sharing the role of boss with eventually" He kind of amazedly took my hand and shook it. He opened his mouth to respond and I held up my hand to stop him "I've been living with CEDEF for two years, I know exactly who you all are, You are 'Smoking Bomb' Hayato, or Hayato Gokudera, your elder sister is Poison Scorpion Bianchi, and you use bombs as weaponry, I have more details but I don't feel like discussing them in front of the Varia"

"Che, We already knew all that trash"

"I know Xanxus that's why I was willing to say it in front of you" I said looking over my shoulder at him "what do you think I am? An idiot? Che" He reddened with anger

"Well, have your idiot father explain what the rules for the battles are, seeing as you showed up late yourself" He said taking his only available remaining pride.

"I already know what the rules are, I got a letter as well, if you had forgotten I've been considered a likely boss candidate my whole life, where as even Tsuna wasn't considered possible until I told them I wouldn't be boss without him" I raised an eyebrow at them "Best of Luck in the battles" I finished calmly.

"Hmph, we won't need luck to beat you trash" Xanxus retorted I gasped.

"Oh, I'm sorry did you misunderstand me? I meant best of luck so that **when** you lose you'll fall on your ass instead of your head; heaven knows you have too few brain cells to begin with" I raised an eyebrow silently challenging him to retort to that.

"Yeah and hell knows you were born with none" I rolled my eyes at his stupid retort "We're leaving"

"I think I have enough brain to figure that out without an announcement, thank you so much Captain Obvious, what will you announce next? Your lack of enough common sense that keeps you from running away screaming like a girl?" His back tensed but he jumped away anyways.

"Good job Decimo! I could seriously imagine you being boss with Juudaime!" Gokudera said clapping me on the back.

"Takeshi-kun" I said faintly.

"Yes Aemi-chan?"

"Catch me, I think I'm going to fall over" He grabbed me as soon as possible once he realized that I was swaying on my feet and therefore, not kidding.

There was a silent question on everybody's faces, 'How can you stand up to Xanxus like that then nearly faint afterwards?' "Sorry about that. Battle Aemi has made her first appearance." I paused before breathing to explain. "I've sort of created this battle ready alter ego, who I call Battle Aemi, Battle Aemi can take care of anything, can burn with the best of them, real Aemi falls over from accumulated stress afterwards" I rubbed my temples "The Varia of course knows about my two different personalities after living with me for half a year thus the reason Bel referred to me as 'Battle Principessa' "

Gokudera snorted as my newly won respect disappeared from his eyes. Ryohei too looked like he was trying not to laugh but Takeshi-san just smiled, and I could hear him mutter under his breath 'cute'.


	4. Chapter 4

I breathed in deep and steel myself before entering through the gates to the school. I was already gathering stares from my surrounding soon-to-be peers.

They were probably wondering what the hell I was doing, showing up in my jeans and t-shirt instead of a uniform.

Particularly the man with the black coat hanging off his shoulders and a bright red armband pinned to the sleeve of his jacket. "Where's your uniform?" He said cruelly as he looked me over, attempting to determine whether I should be there or not. "Student Card" He demanded coldly.

I bit my lip, attempting to contain my retort, but unfortunately for the prefect, battle Aemi had other ideas. "I left it in my other uniform." I grinned cruelly, folding my arms and silently daring him to challenge me.

"Then I am simply forced to bite you to death." I couldn't help but chuckle. I mean seriously, he's going to bite me to death?

"You seriously need a new catchphrase don't you?" I retorted even as I whipped the nunchucks from my bag and began twirling them calmly and shifting them from hand to hand. "For me, I think I'll just have to show you that I am the creature from your nightmares" His gaze hardened, and as I predicted, he slid weapons from his sleeves. Tonfas.

This must be Hibari Kyoya then; the least I can do is play along with his image of a misbehaving student right? No matter how it ended, I had full plans to enjoy this.

"Wao, I'm shaking where I stand" He laughed without humour and a glint entered into his eyes that removed any doubt of whether he thought I was worthy for him fighting with his full strength, I was more then worthy, I was his prey.

I lunged at him before feinting back, just in time for him to miss me with his counterattack. This would be the most fun I had had since the Varia were my housemates. It probably is a bad sign that I think that those experiences are fun, of course they only seem fun in Battle Aemi world, which I seem to be entering far more frequently.

I caught his next swing with my now empty hand as my nunchucks flew into my other hand to swing down hard on his head. He didn't make the slightest sign that he was impressed, just continued to swing at me. I continued to duck.

There was nothing surprising in his fight, nothing that I hadn't seen and studied thousands of times. I chuckled "It's a pity really, that a boy with potential like yours remains trapped behind that pathetic school yo-" I started but corrected myself, I was being a student now, I had to at least pretend to be a member here, or this deliciously entertaining fight will come to an end. "We are forced to call home"

For that comment he whacked on the cheek. As my head whipped to the side I grit my teeth and spat the blood welling up in my mouth onto his pristine white shirt. His eyes which had before only displayed the cruel metallic glean, now shone with a passion for killing so cold that it was a wonder I didn't freeze on the spot.

"Now we're getting somewhere" I said grinning before going on the offensive and attacking at a speed that he could hardly see let alone keep up with. With the upgrade in speed, the casing on my weapons fell away and I began swinging blades with grips instead of harmless chunks of wood. A few more slashes later he was panting and having difficulty standing, blood running down his face from a cut over his eye, and a hand pressed to his side to cut off the bleeding there. I let the casing return before whipping my nunchucks into the back of his knees and knocking him off his feet, had I attacked like that with the blades out, Hibari Kyoya would have lost half his legs.

I grinned as the bell rang. "Guess I should go register and get a uniform now, ne Hibari?" I said even as I held in a laugh at the pathetic face he was showing, it wasn't a face that had been defeated, but instead a face which didn't even seem to realize that he had been defeated, maybe I had been too fast for him to see. "And my dad thought I would get more fighting experience at a military school" I muttered, revelling in the leftover adrenaline from the fight, even though I knew that I wouldn't be able to make it far without collapsing from the after effects of battle Aemi.

This school seemed like it might be more amusing then I thought.


End file.
